Field of the Invention
The present disclosure relates generally to valves and more specifically relates to improving fluid flow through valves.
Description of the Related Art
Various types of valves are known in the art, at least some of which can have a flow rating (or “flow coefficient”) K associated therewith. When fluid flows through a valve or other restrictive device it can lose some energy and a valve's flow rating can be representative of an amount of fluid that passes through the valve over a pressure drop. In other words, the flow rating of a valve can be described as a design coefficient or factor that relates head drop or pressure drop across the valve with a flow rate of fluid in or through the valve. In at least some cases, a valve flow rating (for liquids) can be determined according to the equation:
  Q  =      K    ×          √                        Δ          ⁢                                          ⁢          P                Sg            
wherein Q is the flow rate, ΔP is the pressure drop across the valve, Sg is the specific gravity of the fluid flowing through the valve, and K is the flow coefficient (Cv in imperial units; Kv in metric units). K (hereinafter “Cv”) can be non-dimensional or with units, which can depend on whether parameters such as diameter or density are considered inside the coefficient or equation.
In general, fluid enters a valve through an inlet, passes through an orifice and exits through an outlet. Ideally, in order to achieve maximum flow a valve would be a straight pipe with a smooth surface and laminar flow; any deviations can cause turbulence or other restrictions to the flow, which can lower an overall flow rating. However, valves are not ideal and have varying geometries (bends, rough surfaces, corners, cross-sectional area differences, etc.) that can restrict fluid flow by causing the flow to become turbulent or slowed, which can make for less than ideal valve structures. Valves and valve components can be made in numerous ways, such as by molding, machining, printing and so forth. For example, some valves or valve parts can be made by injecting material into a mold through what is known as a gate. The material can (or ideally should) flow from the gate and around any object in its path (side pulls, pins, etc.) until the mold is completely filled. Plastic and other types of molded valves can have both thin and thick sections of material. The thickness of the material can depend on the design of the valve as well as the material used to mold the valve. In at least some cases, structural failure can be most likely to occur in relatively thin sections, particularly if material inconsistencies are present. For example, knit lines can be created during a mold process when the material flow from a gate is diverted into two or more flows. The two or more flows can recombine in another section(s) of the mold and can weld together forming what is known as a knit line along the intersection. Knit lines can be inherently weaker than other areas in the material due to the material cooling somewhat before welding together. In composite plastics (plastics with some other filler material), for example, the fibers of the filler material may not align properly at the location of the knit line, which can reduce the strength of the formation at that location relative to other locations without knit lines. It can be desirable for plastic and other valves to perform at relatively high pressures and temperatures. However, at such higher pressures and temperatures, knit lines can become a problem for the structural integrity of a valve.
The disclosures and teachings herein are directed to systems and methods for improving valve structures and fluid flow through valves.